The M3 motorway could be delayed again by further legal action, it emerged tonight.
At least two campaigners are to return to the High Court in a bid to block the project going ahead through the historic Hill of Tara in Co Meath.
Protester Vincent Salafia said that "at least two" people — whom he declined to identify — plan to mount a fresh legal challenge soon.
Speaking before a talk at NUI Maynooth tonight, Mr Salafia said there were a number of potential areas of future litigation against the Government.
The law student dropped his long-running Supreme Court case against the project earlier this month on condition he would not have to pay an estimated €600,000 costs incurred in a preceding High Court appeal.
"The remains of at least two national monuments have been found in the area of the motorway in recent times," he said.
"European law is also being studied to bring it to bear on the side of campaigners."
Mr Salafia also claimed that the National Road Authority plans to hold the public consultation for the tolling of the M3 after they sign the Public Private Partnership contract with the tolling consortium.
Meanwhile Independent candidate for next year's Seanad elections, businessman Martin Hogan has signalled that the Tara project will be a key campaigning issue for him.
The Tara Watch group aims to canvass all Dail TDs on their stance on the subject in coming months.
Mr Hogan said: "Environmental campaigns such as these highlight the need to involve people in decisions that affect their lives and the need to move away from corrupt and incompetent government in Ireland once and for all."